Zon 2000 Raw Output

Ibn al-Shatir
Sundial
Great Mosque
Damascus
R T Bailey
BSS Conference
April 2012
Cheltenham
Istanbul: New Mosque Yeni Camii
Yeni Camii
Vertical Declining Sundials
New Mosque
“Yeni Camii” 1
-Local hours 20’
-Italian hours
-Asr 1 & 2
-Declination
-Other curves
Dawn and
Dusk Prayers
• G. Ferrari found
Fajr and Isha
prayer reference
lines on Yeni Camii
pictures
• Sloping down left
14 hours before
Fajr (dawn) –19°
• Curving up 4
hours before Isha
(dusk) –17°
• All 5 prayer times
on this sundial
Istanbul Sundial Tour
Istanbul
• Topkapi Palace
• Complex sundial
in Courtyard
• Asr prayer line
• Italian Hours
• Babylonian
• Equal Hours
Joël Robic ©
http://perso.orange.fr/cadrans.solaires/cadrans/cadran-istanbul-topkapi.html
Italian
Babylonian
Asr
Ottoman Sundial
Missouri Botanical Garden
• Sundial is unique and
significant
• Only Islamic dial in
public use in America
• Only dial with Italian
and Babylonian hours
• Only dial with prayer
times or Qibla
• Shows what western
civilization gained
from the peak of
Islamic science and
culture
• Appropriate for the
Ottoman Gardens
Proud Artisans
• Abraham Mohler
Sculptor
• Roger Bailey
Designer
Ibn al-Shatir Sundial
Year 1371
• Europe: After black death, crusades, Cathars,
Normans, Magna Carta, cathedrals
• Time of Edward III, Charles V, Charles IV, Hundred
Years war, Reconquesta, Chaucer
• Ming Dynasty, after Gengis Khan
• After Golden Age of Islam in Mecca, Cairo and
Damascus, from North Africa, Spain, to India
• Damascus attacked by Mongols from the east, Turks
from the north, crusaders from the west
• Ottoman Empire growing, Byzantine besieged
• Sundials? Greece, Roman hemispheres, Mass dials,
altitude dials, point gnomons, temporal hours
• Many Islamic sundials:planar horizontal, vertical,
polar etc were proper instruments with equal hours
Islamic Sundial Concepts
• Mathematics and instrumentation for astronomy
and timekeeping was well defined in the east
before al-Shatir
• Al-Marrakushi described horizontal sundials with
temporal and equal hours about 1275 to 1282 in
Cairo
• Najm al-Din al-Misri described over 100
different astronomical instruments: sundials,
quadrants, astrolabes, alidades etc about 1330 in
Cairo
• Equal hours but no polar gnomons
Damascus School of Astronomy
Great Umayyad Mosque
• Damascus was the 14th
century world leader in math
& astronomy
• Great clock by Al Khurasani,
1146-1169
• Consultants for Frederick II
• Quadrants by Ibn Ahmad Al
Mizzi, 1326-1349, astronomer
timekeeper
• Ibn al-Shatir the last and
perhaps greatest Damascus
astronomer, mathematician,
Al Mizzi Quadrant 1333
craftsman, timekeeper
©Trustees of the British Museum
Ibn al-Shatir (‫)بن الشاطر‬
• Ala Al-Din Abu'l-Hasan Ali Ibn Ibrahim Ibn
al-Shatir (‫( )ابن الشاطر‬1304 - 1375)
• Arab Muslim astronomer, mathematician,
engineer, instrument craftsman & inventor
• Religious timekeeper (muwaqqit) at
Umayyad Mosque in Damascus
• Best known for his planetary theories
• Sundials with equal hours and polar gnomon
• Trig concepts developed earlier by
Muhammad ibn Jābir al-Harrānī al-Battānī
(858-925) and others
Ibn al-Shatir (‫)بن الشاطر‬
• Planetary theories used Tusi
Couples
• Eliminated Ptolemy’s equant
and eccentrics from
planetary model
• Better fit for observations &
predictions using concentric
nested celestial spheres
• Predated almost identical
math and drawings by
Copernicus almost two
centuries later
• Maintained geocentric model
like Tyco Brahe
Al-Shatir’s Compendium
• Al-Shatir
made this
Compendium
Sundial in
~1360
• Astrolabe
style alidade
on cover
• Equatorial
sundial
• Removable
sundial inside
• Library of
Awqaf in
Aleppo, Syria
• Photo: Rim
Turkmani ©
Compendium
Slider Plate
Upper part is a 180°
Protractor with
10° & 5° = increments
Not a sundial
with a polar gnomon
but an alidade using a
weight on a string.
Also a Qibla showing
the direction to Mecca
from 10 cities.
Lower part is is a polar
sundial at latitude
angle with a point
gnomon peg, equal hour
lines not temporal, and
odd curved line
Photo: Rim Turkmani © Library of Awqaf in Aleppo, Syria
Damascus
Umayyad Mosque
• Mosque built in 715
• Sundial on Minaret
• Ibn al-Shatir made
original in 1371
• Dial damaged in 1880
by al-Tantawi
• Replica now in place
• Original is in a
museum in Damascus
Great Mosque
Damascus Sundial
•
•
•
•
•
•
•
•
al-Shatir sundial 1371
Large 2 m x 1 m dial
Engraved in marble
Polar gnomons for noon
based equal hours
Gap between gnomons is
the point gnomon
Pictures by Dr. Rim
Turkmani, Imperial College
Astrophysics
BBC TV “Science & Islam”
Youtube link
Sundial High on Minaret
Original Sundial in Museum
Central Details on Original
Polar / Point Gnomons
• Al-Shatir’s innovation was
the use of a Polar Gnomon
• Damascus sundial has two
Point & Polar gnomons
• Small gnomon with 2 points
is important
• Lower point is for an
auxiliary sundial
• Larger gnomon shows long
hour lines and form a gap,
the true point gnomon
Polar Point Gnomons
• Point gnomon shows
declination, hours from
noon, sunrise, sunset and
prayer times
• Al-Shatir’s innovation was
the use of a Polar Gnomon
at the latitude angle
• Polar gnomon gives clear
shadow plane hour lines for
distant viewing of equal
hours through the year
• Small auxiliary sundial uses
the lower point gnomon
al-Shatir’s Sundial
Latitude 33.5°
al-Shatir’s Sundial
Why? Islamic Sundials
• Question? When do we pray?
• Astronomers = Mosque timekeeper (muwaqqits)
• Sundial were complex and difficult to read but
impressive scientific instruments
• Five time systems:
– Time systems with equal hours based on noon, sunrise,
sunset, unequal temporal hours and prayer times
• All Moslem prayer times referenced to the sun
–
–
–
–
Zuhr: Noon meridian
Asr: shadow length = noon + gnomon height
Maghrib: sunset shadow disappears
Twilight: Fajr daybreak, Isha nightfall
Prayer Times: Canonical Hours
• Often shown on Mass or scratch dials
on old churches
• Seven times (tides) defined by St.
Benedict’s Rule (6th Century)
–
–
–
–
–
–
–
Matins (Lauds): midnight to dawn
Prime: sunrise (first)
Triece: mid-morning (third)
Sext: noon (sixth)
Nones: midafternoon
Vespers: sunset
Compline: sunset to midnight
Rule of St. Benedict
• CHAPTER XVI
How the Work of God Is to Be
Performed during the Day
• As the Prophet saith: "Seven times
a day I have given praise to Thee"
(Psalms 119:164), this sacred
sevenfold number will be fulfilled by
us in this wise if we perform the
duties of our service at the time of
Lauds, Prime, Tierce, Sext, None,
Vespers, and Complin;
Sext zuhr
Midday
Moslem
Triece
duha
Daily
Prayer Times
Monastic
Nones
asr
Vespers
Sunset maghrib
Nightfall
Compline
isha
Prime Sunrise
fajr Daybreak
Matins
Midnight
Moslem Prayer Times
Defined by altitude of sun
determined by shadow lengths
Zuhrw = Noon + ¼ gnomon height
ZuhrE = Just past Noon meridian
Gnomon
Asr = Noon + gnomon height to
Noon + 2 gnomon heights
Noon Zuhr
Asr
Moslem Prayer Timelines
Zon 2000
Istanbul: Latitude 41º N
Horizontal with Vertical Gnomon
Ibn al-Shatir Sundial
Auxiliary Sundials
• North auxiliary
sundial uses a
vertical point
gnomon to show
temporal hours, 12
unequal hours &Asr
• South auxiliary
sundial uses the
lower point of the
polar gnomon to
show equal hours
from noon, sunrise
and sunset
North Auxiliary Sundial
•
•
•
•
Damascus Lat 33.5°
Vertical Point Gnomon, height 42%
Temporal hour lines, 12 unequal hours, 1 to 11
Asr Prayer line
South Auxiliary Sundial
• Damascus Lat 33.5°
• Lower Point Gnomon, height 42%
• Sunrise Sunset & Noon based hour lines
Analemma Society
• The Analemma Society operates an educational
and scientific facility at Observatory Park at
Turner Farm, near McLean VA
• Charles Olin, President, Analemma Society
• Sundial Garden Project proposes sixty sundials
to interpret the cosmos as used in different
countries, cultures and times
• Commissioned a replica of Al-Shatir’s sundial
for their location, Latitude 39°
Replicate al-Shatir’s Sundial
• Latitude 39° Analemma Park, Virginia
• Design a horizontal sundial with:
–
–
–
–
–
–
Declination lines for solstices and equinox
Hour lines every 20 minutes, every 4 minutes
Babylonian (Sunrise) hour lines every 20 minutes
Italian (Sunset) hour lines every 20 minutes
Moslem Prayer Times: Asr and Zuhr
Prayer Reference Lines: Fajr and Isha
• Use Fer de Vries Zon 2000 for the lines
• Use DeltaCAD to plot and trim the lines
• Use Excel spreadsheet to calculate the
reference lines
Zon 2000 Raw Output
Time lines every 4’
Rise & Set hour lines
Prayer Times
Declination Lines
Trim in DeltaCAD
DeltaCAD Trimmed Version
Declination, Hour, Sunrise, Sunset & Three Prayer Lines
Replicate al-Shatir’s Sundial
Latitude 39°
Twilight: Modern and Ancient
• Twilight?
– How far below the horizon is the sun ?
• Modern Twilights:
– Civil 6°, Nautical 12°, Astronomical 18°
• Ancient: (Moslem)
– Equivalent to astronomical twilight
– Nightfall 17°, Daybreak 19°
– Why? Dark adaptation
Sundial Reference Lines
• Moslem sundials have reference lines
for daybreak and nightfall prayers
– Damascus Mosque,
– Istanbul: Topkapi, Mosques
• Nightfall (Isha):
– 3 and 4 hours before, 45°and 60°
• Daybreak (Fajr):
– 13:20 or 14 hours before, 200° or 210°
– 3 and 4 hours after
Sundial Reference Lines
• Solve for time tw at twilight altitudes
Sin Alt = Sin Dec x Sin Lat +Cos Dec x Cos Lat x Cos tw
• Subtract reference time angle from twilight
• Solve for Altitude and Azimuth for the ref time
– Sin(Az)=Cos(Dec)xSin(tr)/Cos(Alt)
• Project gnomon tip onto sundial plane
– Distance: g = G/Tan Alt
– Solve for x,y coordinates: x = g Sin Az, y = g Cos Az
• Repeat for different declinations and times
• Plot x,y coordinates as a spline
Afternoon
Prayer Times
•Asr afternoon prayer
•Isha Nightfall prayer
•17° below horizon
•3 & 4 hours before
•Fajr Daybreak prayer
•19° below horizon
•14 hours before
•Fajr line is on the alTantawi 1880 replica,
not the al-Shatir
original
Asr Reference Lines
• Solve for Asr Prayer Time
– Shadow Length = Noon Shadow + Gnomon Height
– Sin Alt = Sin Dec x Sin Lat +Cos Dec x Cos Lat x Cos t
• Subtract reference time angle from Asr time
• Solve for Altitude and Azimuth as above and as
– Sin Az = Sin Alt x Sin Lat/ Sin Dec
• Project gnomon tip onto sundial plane
– Distance: g = G/Tan Alt
– Solve for x,y coordinates: x = g Sin Az, y = g Cos Az
• Repeat for different declinations
• Plot x,y coordinates as a spline
Time Before
Asr
•Asr is defined by the
shadow length
•Noon shadow +
gnomon height
•20 minute intervals
for 2 hours before
Asr afternoon Prayer
•All time references
after noon meridian
and Zuhr Prayer
al-Shatir Sundial Lines
• Prayer reference lines require a clock
• Sundial shows equal hours:
–
–
–
–
Noon based equal hour lines with polar gnomon
Sunrise and sunset based equal hours from point
Prayer reference lines use equal hours
Auxiliary sundial shows (temporal) unequal
• Clocks show equal hours
• A sophisticated mechanical clock existed at
the Great Mosque in Damascus
Bab Jayrun Clock, Damascus
Water Clock of
Ridhwan al-Sa'ati
• Clock at Bab Jayrun Gate,
east of Great Uymayyad
Mosque in Damascus
• Built in 1202 by Muhammad
b.’Ali, and son Ridhwan alSa’ati
• Adjustable to track
seasonal hours
• Birds dropped balls for
intervals,
• Doors opened to show hours
• Working model at IBTTM,
Frankfurt
Museum for the History of Science and Technology in Islam
Complete Design
al-Shatir Sundial @ Latitude 39°
Tamerlane Conquest
• “Timur Lane (the Lame)” sacked Damascus in 1399
• Mosque was burned, Astronomy School destroyed
• Ibn Al-Shatir was the last great astronomer
from the Damascus School of Astronomy
• The Turkish Ottoman Empire became dominant
after the death of Timur Lane
• Al-Shatir type Ottoman sundials in Istanbul
– Topkapi Palace, major Mosques, etc
• Science, mathematics, astronomy etc bloomed in
Europe in the Renaissance
• Not so in the Islamic world
Library Hagia Sophia
The End
One Book: Koran
References
•
•
•
•
•
•
I was pleased to collaborate
with Gianni Ferrari on this
research on Islamic sundials
We both benefited by sharing
information and ideas
The book is a detailed and
comprehensive thesis on
Islamic sundials. Seed details
I recommend his book, now
published at significant personal
expense
The text is in Italian, no big deal
as the content is gnomonics
€ 35 + € 10 postage
[email protected]
References &
Acknowledgements
•
•
•
•
•
•
•
•
•
•
•
•
•
“LE MERIDIANE DELL’ANTICO ISLAM” by Gianni Ferrari 2011
“Analemma Society” Charles & Jacque Olin Link
“Sundials in Medieval Islamic Science and Civilization” Len Berggren, NASS, 8-2 June 2001
“The Meridian of Ibn Al Shatir –Umayyad Mosque in Damascus” Gianni Ferrari, unpublished
personal communication
“The Sundial of Ibn Al Shatir” Dr Rim Turkmani, unpublished personal communication
“Science & Islam” Episode 3 “The Power of Doubt” Jim al-Khalili & Rim Turkmani BBC TV
“Astronomy in the Service of Islam”, David A. King, Variorum 1983
“Islamic Astronomical Instruments”, David A. King, Variorum 1987
“In Synchrony with the Heavens” V1 “The Call of the Muezzin” D. A. King, Brill 2001
“World Maps for Finding the Direction and Distance to Mecca” “Innovations and Traditions in
Islamic Science, D. A. King
“Les cadrans solaires de monde de l’Islam (Sundials in the Islamic World)”, Chapter X, Les
cadrans solaires, histoire, théorie,practique” René Rohr, Oberlin, 1986 (This section is in
European editions not North American editions in English, UofT 1970 or Dover 1996)
“Damascus” Salah Zaimeche, Foundation for Science, Technology and Civilization (FSTC)
“Ottoman Sundials” Roger Bailey, NASS Conference, 2008, St Louis